In a conventional time division communication system, there is a long call delay when a terminal establishes a call via a repeater, and the call of the terminal can not be detected during the call delay. In a case that during the call delay, another terminal tries to access the repeater to establish a call, a call collision occurs in an uplink channel, thereby resulting in a call loss and degrading the user experience.
For example, user A initiates a group call through terminal A to inquire who is going for lunch, and users B and C want to respond to the call. If user C request an access to a repeater through terminal C when user B requests an access to the repeater through terminal B to establish a call with terminal A, a call collision may occur between terminal B and terminal C. In this case, the repeater can not transfer a call from terminal B or terminal C to terminal A normally, thus no response is returned to user A.